I grew up using Mac computers, and for a long time, I've wanted something that would allow me to use all those old applications and games in a more convenient setup. I now have the perfect 'retro' Mac, at least for me: an upgraded Mid-2010 Mac Mini.
This compact low-power
I still have one of these, I bought it & set it up as a server 14 years ago so its been powered on the majority of its life, and still functions ok. I've slowly moved most stuff off it and now it kinda just exists as a computer to buy & download albums from iTunes on if I can't get them on bandcamp etc.
If I didn't need OSX for the iTunes part i'd have rebuilt it a long time ago with some more lightweight linux distribution but its doing a job and now i'm reminded of how old it is I kinda want to see if I can get it to 20 years.
I’d be tempted to say that the 2014 Mini is a better bet for retro Mac usage.
It’ll still run Sonoma via OCLP, but has the benefit of USB 3. Bung a huge SSD in there and you can use it as a media server too. I have a 2014 that’s about to become surplus to requirements, so that’s precisely what I intend to do.